The Brompton design may be changing very little but it can't be called stagnant when they are probably the only folding bike manufacturer with a 2 month waiting list. You might call it dead on target. For example at the main Melbourne folding bike shop, you can currently get any Birdy for almost a 50% discount compared to the prices when they were first released; but for any Brompton, sorry sir, get in the 2 month queue.